Why would you expect that? Also, the M4 is faster than the M3, but that doesn't mean Apple couldn't or didn't want to fuse two of them together for an M4 Ultra.

Is an Intel 10700K faster than a 12400F? The generations are different but the chips have vastly different capabilities and features.

M4 is the generation. The modifier modifies the generation. M4 Pro is an M4 with some extra pizzaz. M4 Max is an M4 with lots of extra pizzaz.

The M3 vs M4 thing makes sense, but pro vs ultra vs max is ???

…a modifier to the generation, denoting core count and feature set?

Those names don't make it clear.